SECTION 501 Pesticide Analytical Manual Vol I Control of detector temperature usually is not as critical but should be well controlled, constant, and not affected by such things as line voltage fluctuations 2)Temperature readout should be available for column, detector, and inlet. Check accuracy of instrument temperature indicators with accurate py 3)Instrument design should be simple enough to facilitate troubleshooting and repairs. Design should permit easy removal or inspection of either column or detector without affecting the temperature of the other. 4)System should be designed to prevent or minimize contact between sample injection and any metal parts; system should be all-glass (or as near as possible Several sizes of packed and open tubular capillary columns are used in residue analysis, and hardware for inlet and column must accommodate configurations that will be needed. Section 502, Columns, includes direc tions for adapting equipment. 5) Certain detectors may require multiple heated zones, including combus- tion furnaces For flexibility, designs that permit ready access for servicing nd maintenance are preferred. Section 503 provides details on various detectors used in pesticide residue determination 6) Electrical signal monitoring equipment is usually one of two designs: (1) amplifier with 1 or 10 mV output, compatible with strip chart recorder, d (2)amplifier with I or 10 V output, compatible with data processing by either electronic integrator or computer. Other remote devices such as autosamplers can be easily adapted to any of these systems Other Apparatus Gas Regulators. Two-stage gas pressure regulators with stainless steel diaphragms Poo required for all GLC determinations of trace residues. Regulators with a sec. ary stage maximum pressure of 80 psi are acceptable, but those with 200 psi fer more flexibility. If a hydrogen purifier is used(below), the latter type of regulator is required, because higher pressure is needed Gas lines that connect gas tanks to the chromatograph must be clean and free of components that contain oil or gas-purgeable elastomers; refrigeration grade copper(i.e, cleaned of all oil) is preferred. Tubing (even refrigeration grade) should be sequentially rinsed with methylene chloride and acetone before use Plastic and nylon lines must be avoided to reduce the likelihood of air contami- nating the gas. Syringes. The most common syringes for injection of food extracts into a chro- matograph are 5 and 10 uL fixed needle syringes with 22 bevel points; some other sizes may be needed for special purposes. Hamilton syringes or equivalent are available from all chromatography suppliers. Plunger "guides"are available as options to minimize bending the plunger during injection. 501-2 Transmittal No. 94-1(1/94]501–2 Transmittal No. 94-1 (1/94) Form FDA 2905a (6/92) SECTION 501 Pesticide Analytical Manual Vol. I Control of detector temperature usually is not as critical but should be well controlled, constant, and not affected by such things as line voltage fluctuations. 2) Temperature readout should be available for column, detector, and inlet. (Check accuracy of instrument temperature indicators with accurate py￾rometer.) 3) Instrument design should be simple enough to facilitate troubleshooting and repairs. Design should permit easy removal or inspection of either column or detector without affecting the temperature of the other. 4) System should be designed to prevent or minimize contact between sample injection and any metal parts; system should be all-glass (or as near as possible). Several sizes of packed and open tubular capillary columns are used in residue analysis, and hardware for inlet and column must accommodate configurations that will be needed. Section 502, Columns, includes direc￾tions for adapting equipment. 5) Certain detectors may require multiple heated zones, including combus￾tion furnaces. For flexibility, designs that permit ready access for servicing and maintenance are preferred. Section 503 provides details on various detectors used in pesticide residue determination. 6) Electrical signal monitoring equipment is usually one of two designs: (1) amplifier with 1 or 10 mV output, compatible with strip chart recorder, and (2) amplifier with 1 or 10 V output, compatible with data processing by either electronic integrator or computer. Other remote devices such as autosamplers can be easily adapted to any of these systems. Other Apparatus Gas Regulators. Two-stage gas pressure regulators with stainless steel diaphragms are required for all GLC determinations of trace residues. Regulators with a sec￾ondary stage maximum pressure of 80 psi are acceptable, but those with 200 psi offer more flexibility. If a hydrogen purifier is used (below), the latter type of regulator is required, because higher pressure is needed. Gas lines that connect gas tanks to the chromatograph must be clean and free of components that contain oil or gas-purgeable elastomers; “refrigeration grade” copper (i.e., cleaned of all oil) is preferred. Tubing (even refrigeration grade) should be sequentially rinsed with methylene chloride and acetone before use. Plastic and nylon lines must be avoided to reduce the likelihood of air contami￾nating the gas. Syringes. The most common syringes for injection of food extracts into a chro￾matograph are 5 and 10 µL fixed needle syringes with 22° bevel points; some other sizes may be needed for special purposes. Hamilton syringes or equivalent are available from all chromatography suppliers. Plunger “guides” are available as options to minimize bending the plunger during injection